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PubMed1996

Reproductive strategies of the cat flea (Siphonaptera:Pulicidae): parthenogenesis and autogeny?

The objective of this study was to determine if there is evidence of parthenogenesis or autogenous reproduction in the cat flea, Ctenocephalides felis (Bouché). To examine parthenogenesis, 400 newly eclosed virgin female fleas were collected from a laboratory colony and 100 were placed into each of 4 feeding cages and fed bovine blood through a Parafilm membrane. Three of the feeding cages were monitored for egg production for 7 d and each group of 100 virgin female fleas produced an average 1,119 eggs per cage, but none was viable. Fifty male fleas were added to those 3 feeding cages on day 7, and within 24 h the female fleas began ovipositing fertile eggs and nearly quadrupled their egg output. The other cage in which no males were introduced served as a control and did not produce a single viable egg in the 14-d experimental period. A similar experiment examined the continuance of virgin females to lay nonviable eggs and it was found that they continued to lay nonviable eggs for at least 58 d. Egg production was also studied in unfed fleas and it was found that unfed fleas did not produce eggs. These results suggest that neither parthenogenetic reproduction nor autogeny are exhibited by the cat flea.

Animals↗
PubMed1998

Host grooming efficiency for regulation of cat flea (Siphonaptera: Pulicidae) populations.

Grooming efficiency was studied by infesting domestic short-hair cats, Felis catus L., with known numbers of cat fleas, Ctenocephalides felis felis Bouché, then collecting the cat feces and extracting the fleas to determine how many had been groomed off, varying the infestation level. Some hosts were found to be significantly more efficient at grooming fleas than others, with the best groomer removing 17.6% of its flea burden daily, compared with only 4.1% removed by the poorest groomer. Cats were more efficient at grooming fleas at infestations of < 50 fleas and > 150 fleas. Mean on-host flea longevity was 7.8 d.

Animals↗
PubMed2000

Quantities of Yersinia pestis in fleas (Siphonaptera: Pulicidae, Ceratophyllidae, and Hystrichopsyllidae) collected from areas of known or suspected plague activity.

We used a quantitative competitive polymerase chain reaction (PCR) (QC-PCR) to determine bacterial loads in 669 fleas collected in areas of confirmed and suspected plague epizootics. Fleas were collected out of rodent burrows (67.9%) and off of captured animals (24.1%) and rodent carcasses (8.1%). An initial PCR screening assay indicated that 12.1% (81/669) of all fleas were positive for Yersinia pestis. Fleas collected from burrows had significantly lower (chi2 = 264.9, P < 0.0001) infection rates (6.8%) but significantly higher (Student t-test, P < 0.0001) bacterial loads (mean = 10(5.6) Y. pestis per flea) than fleas collected off of rodent carcasses (infection rate = 92.6%; mean bacterial load = 10(4.8) Y. pestis per flea). None of the fleas collected off of captured animals were positive for Y. pestis by PCR, although seven of the 176 captured animals were serologically positive for Y. pestis.

Animals↗
PubMed1990

Detection of murine typhus infection in fleas by using the polymerase chain reaction.

Polymerase chain reaction (PCR) amplification of DNA was used to detect the etiologic agent of murine typhus, Rickettsia typhi, in experimentally infected adult fleas. A primer pair derived from the 17-kilodalton antigen sequence of typhus and spotted fever group rickettsiae was used to amplify a 434-base-pair (bp) fragment of the genome of the murine typhus rickettsiae. The amplified 17-kilodalton protein antigen-specific sequence was detected in ethidium bromide-stained agarose gels in individual fleas as early as 2 days after exposure to rickettsemic rats (two of six tested). The 434-bp sequence was not detected in uninfected control fleas. A dot hybridization assay used to detect the 434-bp fragment was also specific and about 100-fold more sensitive than the agarose gel PCR assay. Since the PCR assay employed a boiled extract of triturated fleas, both PCR and an antigen capture enzyme-linked immunosorbent assay (ELISA) could be performed on the same individual flea homogenate. The ELISA identified 12 infected fleas out of 29 randomly selected fleas, compared with 14 specimens which were positive by PCR. The PCR assay detected rickettsiae in samples in which no viable rickettsiae were detected by plaque assay. Like the ELISA, the PCR assay sensitivity was due in part to its suitability for detecting small numbers of both live and dead R. typhi in fleas.

Animals↗
PubMed2000

Effects of a new insect growth regulator, CGA-255'728, on the different stages of the cat flea (Siphonaptera: Pulicidae).

A new juvenile hormone mimic CCA-255'728, developed by Novartis, was tested for its efficacy on different life stages of the cat flea, Ctenocephalides felis (Bouché). The compound was mixed in bovine blood at concentrations of 1, 10, and 100 ppb and fed to adult fleas using an artificial membrane system. Less than 7% of the eggs from fleas fed 10 and 100 ppb hatched, compared with >70% hatch in eggs laid by control fleas or fleas fed 1 ppb. Histological studies demonstrated that approximately 50% of the eggs from fleas fed 10 ppb contained unhatched larvae that died after completing embryological development. At 100 ppb, 24% of the fleas died as fully formed larvae within the egg, but at this concentration nearly 20% of fleas also died before embryogenesis was completed. In addition to embryonic and larval mortality, approximately 28% of eggs from the 100 ppb-treated group were deposited as empty shells. Evidently these eggs were crushed by the muscular action of the oviduct and yolk was expelled into the oviduct during oviposition. None of the test concentrations showed adulticidal effects over a 10-d period. Fecundity was significantly increased with increased concentrations of CGA-255'728 indicating that the compound mimicked the effect of juvenile hormone.

Animal Feed↗
PubMed2001

Effects of juvenile hormone on eggs and adults of the cat flea (Siphonaptera: Pulicidae).

Juvenile hormone III plays a major role in regulating feeding and reproduction in the adult cat flea, Ctenocephalides felis (Bouché). Both blood consumption and egg production increased in a dose-dependent manner up to a maximum at 1,250 ppm when fleas were continuously exposed to concentrations up to 12,500 ppm juvenile hormone. Histological studies demonstrated that juvenile hormone III also stimulated cellular differentiation of salivary gland epithelia, midgut epithelia, and fat body cells, enhancing the ability of the adult flea to digest blood and synthesize vitellogenins for the maturing oocytes. In unfed fleas, exposure of adults to concentrations of > or = 1,000 ppm juvenile hormone III applied to filter paper resulted in membrane lysis and destruction of salivary gland and midgut epithelial cells, fat body cells, and ovarian tissue. Unlike juvenile hormone mimics, which have potent ovicidal effects in fleas, juvenile hormone had little effect in preventing egg hatch; 58% of the eggs laid by fleas treated with 12,500 ppm juvenile hormone III hatched, and a concentration of 30,000 ppm was required to reduce hatch to 2% in untreated eggs exposed to treated filter paper for 2 h. Compared with the juvenile hormone mimic pyriproxyfen, juvenile hormone III was less toxic to fed adult fleas. However, at a concentration of 12,500 ppm, juvenile hormone killed approximately 45% of the adults and caused autolysis and yolk resorption in the developing oocytes. Thus, at high concentrations, juvenile hormone appears to have a pharmacological effect on fleas, which is highly unusual in insects.

Animals↗
PubMed2000

Efficacy of nitenpyram as a systemic flea adulticide in dogs and cats.

In a clinical trial involving 123 cats and 88 dogs, the efficacy of tablets containing nitenpyram against natural flea infestations was investigated. The animals were selected from the routine cases of nine veterinary clinics in the UK and 143 were treated with the tablets and 68 control animals were treated with placebo tablets. Each animal was maintained in an individual cage. The time when the first fleas fell off each animal was recorded between 30 minutes and five hours after treatment, and six hours after treatment the numbers of live, moribund or dead fleas on each animal were determined, and the flea survival rate was calculated. The drug's efficacy was assessed by comparing the mean survival rates of fleas on the treated and control animals. Fleas started to fall from the animals 30 minutes after treatment and two hours after treatment some fleas had detached from 81 per cent of the treated animals. After six hours the efficacy of the drug reached 96.7 per cent on dogs and 95.2 per cent on cats, and 85.9 per cent of the fleas were found off the treated animals, compared with 1.8 per cent in the controls. No adverse drug reactions were recorded during the trial.

Animals↗
PubMed2002

Time of survival under starvation in two flea species (Siphonaptera: Pulicidae) at different air temperatures and relative humidities.

We studied the effect of air temperature and RH on the survival time of adult Xenopsylla conformis Wagner, 1903 and Xenopsylla ramesis Rothschild, 1904 fleas during starvation to explain the paratopic habitat distribution of these species on opposite ends of a precipitation and temperature gradient in the Negev Highlands, Israel. We hypothesized that the pattern of distribution of the two flea species is caused by differential microclimatic preferences of imagoes and predicted that (1) the resistance to starvation would differ between the two flea species at different air temperatures (10 degrees C - 38 degrees C) and relative humidities (RH) (40%-92%) and (2) survival time of starving X conformis would be longer than that of starving X ramesis at high air temperatures and low RHs. Survival time of newly emerged X conformis was dependent on air temperature but not on RH, whereas in newly emerged X ramesis it was affected by both air temperature and RH. Generally, survival time of newly emerged fleas was longer at lower air temperatures and higher humidities than at higher air temperatures and lower humidities. No significant difference in survival time between species in dependence on either air temperature or RH were found for newly emerged fleas. Fed fleas of both species responded similarly to changes in air temperature and RH in terms of survival time. Survival time at lower temperatures was longer than that at higher temperatures. Females survived longer than males at all air temperatures except for the highest temperature when the survival time of both sexes was similarly low. In both species, the effect of RH on survival time was significant at the highest RH only, with a decrease in survival time at 92% RH. In contrast, survival times at lower RHs did not differ. Males of both species survived for less time than females at all RHs. X conformis generally survived for less time than X ramesis, all else being equal. The only regime at which X conformis survived longer than X. ramesis was 38 degrees C and 40% RH. Newly emerged fleas survived for significantly longer time than fed fleas.

Adaptation, Physiological↗
PubMed2005

Comparative speed of kill of selamectin, imidacloprid, and fipronil-(S)-methoprene spot-on formulations against fleas on cats.

The speed of kill of selamectin, imidacloprid, and fipronil-(S)-methoprene against Ctenocephalides felis infestations on cats for one month following a single treatment was evaluated. Eighty cats were randomly allocated so that there were 20 cats in four different treatment groups. On Days -2, 7, 14, 21, and 28, each cat was infested with 100 adult C. felis from the Kansas 1 flea strain. Following initial application only imidacloprid had caused a significant reduction in adult fleas on treated cats within 6 hours, but by 24 hours all three formulations had killed 96.7% of the fleas. At 7 days post treatment, all three formulations reduced flea populations within 6 and 24 hours by 68.4% and 99.4%, respectively. At 21 and 28 days after treatment, none of the formulations killed significant numbers of fleas as compared to controls within 6 hours of infestation. At 28 days after treatment, selamectin, fipronil-(S)-methoprene, and imidacloprid had killed 99.0%, 86.4%, and 72.6% of the fleas within 48 hours of infestation, respectively. This study demonstrates that the speed of kill of residual flea products on cats decreases throughout the month following application. It also demonstrated that selamectin provided the highest level of residual activity on cats against the Kansas 1 flea strain.

Administration, Cutaneous↗
PubMed1995

Fleas (Siphonaptera) of cotton mice on a Georgia barrier island: a depauperate fauna.

From February 1993 through October 1994, 382 cotton mice Peromyscus gossypinus were live-trapped and examined for fleas on St. Catherines Island, Liberty County, Georgia. Orchopeas leucopus was the only species of flea collected, with an overall prevalence of 27% and a mean intensity of 3.8. This flea was more abundant on cotton mice during the cooler months, with peak infestation indices recorded in March 1993 and in January 1994. Five species of fleas (Polygenis gwyni, Stenoponia americana, Ctenophthalmus pseudagyrtes, Peromyscopsylla scotti, and O. leucopus) were collected from 29 cotton mice live-trapped in adjacent mainland localities during the same period. The depauperate flea fauna of cotton mice on St. Catherines Island suggests that either the original colonizing cotton mice were infested by only 1 species of flea (O. leucopus) and that no subsequent invasions of cotton mouse fleas have occurred, or that other cotton mouse fleas cannot establish on the island.

Animals↗
PubMed1993

The seasonal abundance of Gerbillus pyramidum and their flea ectoparasites in Al Arish, North Sinai Governorate, Egypt.

The seasonal abundance and the flea ectoparasites of Gerbillus pyramidum were studied. The results showed that the jerboa was more common in Summer (jerboa index 0.43) and least common in Winter (jerboa index 0.35). The overall male to female ratio was 4.2:1. The flea ectoparasites were more common in Autumn (flea index 10.5) and least common in Summer (flea index 6.8). The overall flea index was 8.75 and the majority of fleas (90.9%) was collected on male jerboa. The collected fleas in a descending order of abundance and flea index were: Xenopsylla cheopis (3.1), X. ramesis (2.7), Stenoponia tripectinata (1.4), Nosopsylla sinaiensis (0.9), Hopkinsipsylla occulta (0.6), and Pulex irritans. (0.01).

Animals↗
PubMed1997

Comparison of flea control strategies using imidacloprid or lufenuron on cats in a controlled simulated home environment.

OBJECTIVE: To compare the effect of monthly treatments with imidacloprid (an adulticide) or lufenuron (an insect development inhibitor) for protecting cats against Ctenocephalides felis felis in a simulated home environment. ANIMALS: 3 matched groups of 4 cats each. PROCEDURE: A self-propagating flea life cycle continuously exposing cats to 'natural' infestation was established in 3 pens. Small artificial infestations were later superimposed to mimic the effect of a cat roaming outdoors and acquiring extraneous fleas. One pen housed an untreated control group, and the other 2 pens housed cats treated every 28th day with an imidacloprid spot-on formulation or lufenuron suspension, respectively. Flea counts were performed at 14-day intervals for 112 days. RESULTS: Flea numbers increased on control cats around day 42 when mean counts on cats in the imidacloprid and lufenuron groups decreased by 100 and 86.8 percent, respectively. Fleas were not found on any imidacloprid-treated cat, but lufenuron-treated cats were consistently parasitized. CONCLUSIONS: Imidacloprid administered at monthly intervals maintained flea burdens below the limit of detection, whereas clinically important flea populations developed in the lufenuron treatment pen. CLINICAL RELEVANCE: Results from this experimental model suggest that flea populations within a home may be controlled by carefully timed on-host treatments with potent long-acting insecticides such as imidacloprid.

Administration, Cutaneous↗
PubMed1985

Fleas on roof rats in six areas of Los Angeles County, California: their potential role in the transmission of plague and murine typhus to humans.

Roof rats (Rattus rattus) in southern California are rarely involved with plague epizootics and murine typhus. Little evidence exists implicating these rodents as sources of human infection. This might be explained by the absence of fleas capable of transmitting these 2 diseases. From February 1981 through January 1982, roof rats were live-trapped and examined for fleas each month in 4 areas of Los Angeles County. Two other areas were trapped for 9 and 3 months respectively. Areas sampled were in or near the suburban-wilderness fringe where plague and murine typhus occur, and where roof rats coexist with a variety of wild and domestic mammals and humans. From 1,206 roof rats, 827 fleas belonging to eight species were collected. Leptopsylla segnis (54%) and Nosopsyllus fasciatus (39%) were the most abundant and together comprised 93% of all fleas. Xenopsylla cheopis was not found. The relative abundance and diversity of fleas on roof rats varied considerably between areas, making it difficult to predict flea diversity and abundance in unsurveyed areas where similar conditions exist. However, the overall low flea indices and the absence of X. cheopis help to explain why roof rats in Los Angeles County are rarely involved with plague and murine typhus.

Animals↗
PubMed1985

IgE and IgG antibodies to flea antigen in differing dog populations.

A radioimmunoassay was developed for the detection of IgG and IgE canine antibodies against partially purified flea antigen. Low background levels were found in flea naive dogs, but high levels of both IgE and IgG antibodies were found in many sera from dogs with clinical flea hypersensitivity. In sera from non-allergic dogs exposed chronically to fleas, IgE levels differed little from background, and levels of IgG anti-flea antibodies were much lower than those from the flea allergic group. The results suggest that chronic flea exposure may result in partial or complete tolerance rather than hyposensitization in the commonly accepted sense.

Animals↗
PubMed2004

Respiratory gas exchange in the desert flea Xenopsylla ramesis (Siphonaptera: Pulicidae): response to temperature and blood-feeding.

Xenopsylla ramesis is a flea species parasitizing gerbilline rodents in the deserts of the Middle East. This study was undertaken to determine metabolic requirements of the different developmental stages of the flea-life cycle as well as to investigate the metabolic response to temperature and starvation after blood feeding. A high resolution respirometry system was used to measure CO2 emission of fleas ranging in size from 0.166+/-0.006 mg (larvae) to 0.263+/-0.009 mg (adults). The free-living stages (larvae and adults) had significantly higher metabolic rates than the cocooned stages (pupae). CO2 emission rates of the larvae exceeded that of the adults by 2.6-fold and the pupae by 7.3 times. In the adults, both temperature and blood feeding significantly affected starvation-level metabolism. Metabolism was temperature dependent with an average Q10 of 2.57 for females and 2.55 for males over the temperature range of 10-30 degrees C. No consistent decline in thermal sensitivity at higher ambient temperatures was evident. Fleas that had a blood meal prior to starvation had significantly higher metabolic rates (0. 86 +/- 0.008 x 10(-3) ml mg(-1) h(-1)) than fleas, which were newly emerged unfed adults (0.56 +/- 0.1 x 10(-3) ml mg(-1) h(-1)). Water content also differed between fed (range approx. 67-69% body mass) and newly emerged adults (range approx. 73-75% of body mass). Feeding may stimulate some as yet undetermined physiological process that causes differential metabolic response in starving, fed and unfed fleas. Characteristics of gas exchange in desert-dwelling fleas are reflective of the off-host life style in the protected microenvironment of the host nest or burrow, rather than as a response to any type of environmental extreme.

Age Factors↗
PubMed2004

Identification of mutations associated with pyrethroid resistance in the para-type sodium channel of the cat flea, Ctenocephalides felis.

Knockdown resistance (kdr) to pyrethroid insecticides is caused by point mutations in the pyrethroid target site, the para-type sodium channel of nerve membranes. This most commonly involves alterations within the domain II (S4-S6) region of the channel protein where five different mutation sites have been identified across a range of insect species. To investigate the incidence of this mechanism in cat fleas, we have cloned and sequenced the IIS4-IIS6 region of the para sodium channel gene from seven laboratory flea strains. Analysis of these sequences revealed two amino acid replacements at residues previously implicated in pyrethroid resistance. One is the 'common' kdr mutation, a leucine to phenylalanine substitution (equivalent to L1014F of housefly) reported previously in several other insects. The other is a threonine to valine substitution (equivalent to T929V) and is a novel variant of the T929I mutation first identified in diamondback moth. The L1014F mutation was found at varying frequency in all of the laboratory flea strains, whereas the T929V mutation was found only in the highly resistant Cottontail strain. We have developed rapid PCR-based diagnostic assays for the detection of these mutations in individual cat fleas and used them to show that both L1014F and T929V are common in UK and US flea populations. This survey revealed a significant number of fleas that carry only the V929 allele indicating that co-expression with the F1014 allele is not necessary for flea viability.

Amino Acid Sequence↗
PubMed2006

Epidemiology of flea infestation of ruminants in Libya.

The results of an epidemiological and clinical study of flea infestations of farm animals in northern Libya is reported. Of 12,130 sheep examined from 124 flocks, 150 sheep were found to be infested with fleas from 50 different flocks. Likewise 23 goats from 2981 examined, and 11 calves from 1124 cattle examined were infested No fleas were recovered from camels or horses. Of 1861 fleas recovered from farm livestock, 1857 were Ctenocephalides felis strongylus and 4 were Pulex irritans. Dogs from farms and local clinics were also examined. Eight farms dogs were found to be infested with P. irritans. Of 79 infested dogs examined in veterinary clinics, 53 were found infested with P. irritans, 11 with Ctenocephalides felis felis, 12 had a mixed infestation of P. irritans and C. felis felis. Single dogs had mixed infestation of P. irritans and C. canis; C. felis felis and C. canis; and P. irritans, C. felis felis and Echidnophaga gallinacia. C. felis felis was also found on 15 infested cats. C. felis felis was never found on large farm animals despite frequently sharing their environment with dogs or cats. Likewise C. felis stongylus was never isolated from dogs or cats. This is consistent with the hypothesis that C. felis strongylus has become adapted to large farm animals, whilst C. felis felis is better adapted to dogs and cats. However, four stockmen were found infested with a total of 176 C. felis strongylus, which suggests that this subspecies is also a potential zoonosis. A significantly higher proportion of intensive farms had animals with flea infestation compared to semi-intensive farms. Fleas were not found in nomadic herds. Infested farm animals often presented with excoriation, alopecia, pruritus and hyperkeratitis particularly on the lower limbs. These signs are consistent with the generation of flea-bite hypersensitivity.

Animal Husbandry↗
PubMed2000

Control of fleas on naturally infested dogs and cats and in private residences with topical spot applications of fipronil or imidacloprid.

Thirty-four flea-infested dogs and cats residing in 20 homes in Tampa, FL were randomly placed into 1 of 2 treatment groups during the summer of 1997. Pets were treated topically with either 10.0%w/v imidacloprid or 10%w/v fipronil spot-on on day 0, then once for every 28-30 days for 90 days. Flea populations were assessed in the environment using an intermittent-light trap, while pet flea burdens were assessed using visual area counts. A single application of imidacloprid was 95.3 and 97.4% effective in reducing flea populations on pets at 7 and 28 days, respectively. A single application of fipronil was 97.5 and 97.0% effective in reducing flea populations on pets at the same time points. Following 3 monthly applications of either imidacloprid or fipronil, flea burdens on pets were reduced by 99.5 and 96.5%, respectively. In addition, flea numbers in the in-home environment were reduced by 99. 0 and 98.6% in homes, where pets were treated with imidacloprid or fipronil, respectively.

Administration, Topical↗